from __future__ import print_function
import mercantile
import urllib
import time
import os


def download_tile(tileurl, tile, output_dir, pause=1):
    url = tileurl + '/{z}/{x}/{y}.png'.format(**tile.__dict__)
    local_path = url.replace(tileurl, output_dir)
    print(url, '===>', local_path)

    if not os.path.exists(local_path):
        try:
            os.makedirs(os.path.dirname(local_path))
        except OSError:
            pass
        urllib.urlretrieve(url, local_path)
        time.sleep(pause)  # be kind


if __name__ == "__main__":
    zooms = [7, 8, 9, 10]
    bounds = -123.40, 45.47, -122.42, 46.33  # W, S, E, N
    tileurl = 'http://a.tile.openstreetmap.org'
    output_dir = '/tmp/osm'
    
    for tile in mercantile.tiles(*bounds, zooms=zooms):
        download_tile(tileurl, tile, output_dir)